Bistable fluid device



July 22, 1969 E, A, MAYER 3,456,667

BISTABLE FLUID DEVICE FilegMay l5, 1966 2 Sheets-Sheet l if: l, WVVL/iff @Q/, "7 E /f -gJ/f L I Qjwlf fj] 2J# T Di j :l aufruf l 171%@ /7/ydyfvf E. A. MAYER July 22, 1969 .2 Sheets-Sheet 2 Filed May l5, 1966United States Patent O U.S. Cl. 137-815 10 Claims ABSTRACT F THEDISCLOSURE A bistable vortex device having a divergent exhaust portproviding two stable output pressure distributions in response tovortical ow rate of uid in the device.

This invention pertains to a bistable fluid device and more particularlyto a vortex device wherein supply iluid is admitted to a cylindricalchamber and control iluid, admitted to the chamber through controlports, imparts a vortical ow to the supply fluid which emerges from anexhaust port at the center of the cylinder.

It is an object of this invention to provide in such a vortex device twostable output conditions for a given supply pressure and controlpressure.

It is an object of this invention to provide in such a vortex device ofthe previous object means for supplying incremental control pressure inone instance to reinforce the vortical ow and in another instance tooppose the vortical ilow, to determine which bistable state at which thevortex device is operating by observing any change in the output flow orpressure.

It is an object of this invention to provide such a bistable vortexdevice by having an exhaust port which has an increased diameter in thedirection of the exhaust ilow to induce the formation of an area ofreduced pressure along the walls of the exhaust port at which time isprovided a sudden increase in output ow and pressure, and will provide acorresponding sudden decrease in output ow and pressure when the area ofreduced pressure is removed; with the sudden increase occurring at adifferent supply pressure than the sudden decrease thereby providing ahysteresis loop.

It is an object of this invention to provide the increase in diameter ofthe exhaust port gradually thereby forming a cone shaped surface.

It is an object of this invention to increase the diameter of theexhaust port in a step from a smaller diameter to a larger diameter.

These and other objects will become more apparent when preferredembodiments of this invention are considered in connection with thedrawings in which:

FIGURE 1 is a section taken at 1-1 of FIGURE 2 and shows a schematicView of a preferred embodiment;

FIGURE la is an enlarged section of a modied stepped exhaust port;

FIGURE 2 is a section taken at 2 2 of FIGURE l;

FIGURE 3 is a graph showing three hysteresis loops with the abscissabeing supply pressure PS and with the ordinate being output pressure POwith the three hysteresis loops being for three different controlpressures;

FIGURE 4 is an enlarged sectional view showing the chamber providedabout the exhaust port at the area where the reduced pressure is formed;and

FIGURE 7 is an enlarged section taken at 7-7 of FIGURE 6.

In FIGURE l is shown vortex device 20 having cylin- ICC drical housing22 with a plate 23 covering one end thereof. A supply port 24 is formedin housing 20 and is connected to a fluid supply 25. A button 26 isinserted in housing 22 and is spaced from wall 23 thereby forming achamber 27 therebetween. Also, button 26 is spaced from walls of housing22 to form an annular clearance 28 therebetween.

A control inlet 29 is formed centrally of button 26 ,and is connected toradial passages 30 each of which terminate in a nozzle 32 which, undersuflicient control pressure from source 31, will direct fluid intoannular space 28 causing uid supply passing through port 24 to swirl orassume a vortical flow which increases in rate as it moves towardsexhaust port 44 which is formed centrally of wall 23 within annularextension 45.

A signal tube 34 is provided through housing 22 and through button 26and is connected to passage 36 and jet 38 and introduces fluid flow fromsignal generator 35 which aids the ow from jets or nozzles 32.

A second signal tube 40 also connected to signal generator 35 passesthrough the wall of housing 22 and through button 26 connecting topassage 42 and nozzle 43 to introduce a dlow in annular space 28 whichopposes the ow from nozzles 32.

Exhaust port 44 increases in diameter in the direction of exhaust ow toform a conical like surface 46. As can be seen in FIGURE 1, the exhaustport length is greater than its inlet diameter D. This surface couldalso be increased as shown in the cross section of FIGURE la whereexhaust port 44 has two diameters; a smaller diameter and a steppedlarger diameter 44a. As will become apparent, it is this increase indiameter which provides structure for developing the bistable nature ofthis invention.

An annular wall 52 is connected to plate 23 and forms a vent chamber 54about exhaust port extension 45. Vent port 56 connects chamber 54 to apressure less than the supply pressure Ps, which may be atmosphericpressure in this embodiment.

A pickoif tube 58 is axially aligned with exhaust port 44 and axiallyspaced therefrom. The pressure in tube 58 corresponds to the ow emergingfrom port 44. The flow emerging from port 44 has an axial portion whichis surrounded by a conical portion with the axial portion diminishingand the conical portion increasing as the amount of swirl in chamber 27is increased due to increased control pressure PC. As control pressurePC is increased, the output ow is decreased and the axial portion of thestream is decreased thereby decreasing the pressure in tube 58 and thereading on pressure gauge 59. However, as the swirl is decreased due toa decreased pressure control PC, the axial flow and the total ilow fromport 44 is increased and the pressure in tube 58 is correspondinglyincreased.

Operation In normal operation of the device shown in FIGURES 1 and 2, apressure control bias, Pc Bias, is applied to passage 29 to establish anoperatingrange which may be increased or decreased by applying a signalflow to jets 38, 43 respectively. As the supply pressure is increasedfrom zero, the output pressure will follow line A in the hysteresis loopmarked PC Bias which is the center loop in the graph of FIGURE 3. Whenthe output pressure reaches point B, there will be a sudden increase asshown by line C to point C online D where an increase in supply pressurewill result in a gradual increase in output pressure P0.

As the supply pressure PS is decreased, the output pressure P0 willfollow line D until point E where there is a sudden decrease in outputpressure as shown by line F until it intersects at point F with line Aand then any further decrease in supply pressure will cause outputpressure to follow line A. A resultant hysteresis loop is formed asshown in FIGURE 3.

While it is not definitely understood the exact reason for thehysteresis loop, one possible explanation will be made in connectionwith FIGURES 4 and 5. FIGURE 4 shows the flow from exhaust port 44during the operation on line A in the graph of FIGURE 3 and it is seenthat the flow is close against the ared walls `46 with a slightrecirculation flow R, R taking place. Recirculation ilow R, R' tends toreduce the amount of ow coming from port 44. FIGURE 5 shows the flowfrom port 44 at point B on line A in the graph of FIGURE 3 and here itis seen that the flow has separated from the ilared walls 46 and thereis created an annular region of reduced pressure V which increases thepressure drop through port 44 thereby increasing the flow therethroughwhich accounts for the jump in output pressure to line D in the graph ofFIGURE 3. Also aiding in this sudden increase of output pressure is thefact that the recirculation ilow R, R', has been largely eliminatedthereby reducing resistance to output flow from port 44.

It has been found that when the included angle a of Hare 46, also shownin FIGURE 1a, is in a range between 5 and 45 degrees, the advantages ofthis invention can be achieved. If the tiare angle alpha is too small,the ow will not separate from the iiare walls to form the annular ring Vof reduced pressure and if the flare angle alpha is too large, the flowis not able to attach to the walls 46 at all. For smaller angles ofalpha, the higher the swirl of fluid coming from port 44, which iscaused by a higher control pressure PC, the lower the chance that anarea of reduced pressure V will be formed. I-Iowever, the more swirl tothe air leaving the exhaust port 44, the larger the are angle alpha canbe and still obtain an area of reduced pressure V. In other words, theswirl tends to force the flow against the iiared walls and a largerangle alpha is needed to develop a vacuum region V.

It is therefore seen in the graph of FIGURE 3 that for a given supplypressure PS1, there are two stable output states, those being shown atpoints 1, 2. The stable states can be changed by either decreasing thesupply pressure PS below the point F", in the event that the stablestate is at point 1, or -by increasing the supply pressure to point B,in the event the stable state is at point 2, and then in both casesreturning the supply pressure to PS1.

The stable states can also be changed by changing the pressure controlbias, PC Bias. In the graph of FIGURE 3 are shown two additionalhysteresis loops one labeled PC Bias-APC and PC Bias+APC. PC Bias-APCcan be obtained by supplying a duid signal to tube 40 which will cause aow APC from nozzle 43 which opposes and hence reduces the PC Bias flowfrom nozzles 32. PC Bias-i-APC loop can be obtained by causing a fluidsignal APC to pass through tube 34 and out nozzle 38 aiding the swirlcaused by the PC Bias iiow from nozzles 32.

If the embodiment of FIGURE l is operating at state 1 and a APC isapplied by a iiuid signal through nozzle 43, the operating point will gofrom 1 to 4 and upon removal of the -APC signal, the operating pointwill return to 1 resulting in no output pressure P0 change. However, ifthe operating point is at 2 and a APC is initiated, the operating pointwill again go to 4 and when the APC signal is removed, the operatingpoint will go to 1 resulting in a substantial output pressure P0 changesignifying that the stable state was at point 2.

The operating point may also be determined by application of a -f-APCsignal obtained by applying a fluid signal through nozzle 38. If theoperating point is at point 1 and a +=APC signal is applied, theoperating point will go to point 3 and upon removal of the -l-APCsignal, the operating point will go to point 2 resulting in asubstantial change in output pressure P0. If, however, the operatingpoint is at point 2, application of a -l-APC pressure through nozzle 38will result in the pressure going to point 3 and removal of the I-l-APCsignal will cause the operating point to return to point 2 with nochange in output pressure P0 being noticeable at gauge 59.

If desired, output iiow can be plotted against supply pressure in thegraph of FIGURE 3 and this could be done by modifying the device ofFIGURE l to eliminate the pickol tube 58 and by applying a iiowmeter topassage 56. The output flow would vary in the same manner as shown inthe hysteresis loops in the graph of FIGURE 3 although the outputpressures obtainable would be some- -what lower than those obtainablewith the use of pickoi tube 38.

Embodiment of FIG-URE 6 Another embodiment for obtaining a pressureindication of the stable state to which the vortex device is operatingis shown in FIGURES 6 and 7. In FIGURE 6 is shown a section of exhaustpassage 44 wherein a plurality of radial passages 62 are formed at thatpoint on wall 46 where the area of reduced pressure V occurs. Annulus 64connects each of the passages 62 to output port 66 which is connected topressure gauge 68. When there is an area of reduced pressure formedalong wall 46 which corresponds to a higher output pressure indicatingoperation at point 1, the pressure at gauge `68 will be substantiallyreduced. However, when there is no area of reduced pressure,corresponding to a lower output pressure and opera tion at point 2, thepressure in gauge 68 will be relativel high.

Although this invention has been disclosed and illustrated withreference to particular applications, the principles involved aresusceptible to numerous other applications which will be apparent topersons skilled in the art.

Having thus described my invention, I claim:

1. An apparatus comprising:

housing means providing a chamber for containing vortical ow;

means including a supply port adapted to be connected to a source offluid for providing a preselected first vortical iiow rate of said iluidin said -chamber and a preselected second vortical ow rate of said huidin said chamber, said first vortical ow rate being greater than saidsecond vortical flow rate;

said housing having an exhaust port for egress of said fluid, saidexhaust port having means including a predetermined divergence in thedirection of iiuid tiow for providing a first stable pressuredistribution downstream of said exhaust port at said iirst vortical flowrate characterized by having a iirst pressure central of said exhaustport and further which provides a second stable pressure distributiondownstream of said exhaust port at said second vortical flow ratecharacterized by having a second pressure central of said exhaust portbeing greater than said lirst pressure; and

pressure responsive means operably associated with said exhaust port forproviding an output signal indicative of said rst and second stablepressure distributions.

2. The apparatus of claim 1 wherein said exhaust port is continuouslydivergent.

3. The apparatus of claim 1 wherein said exhaust port is a conicalopening having an included angle in the range of 5 and 45.

4. The apparatus of claim 1 -wherein said exhaust port is of circularcross section and has an inlet diameter D and a length which is at leastD.

5. The apparatus of claim 1 wherein said exhaust port is of circularcross section and has a first diameter for receiving said fluid and asecond diameter downstream of said first diameter forming a stepoutwardly from the first diameter.

6. The apparatus of claim 1 wherein said means for providing said firstand second vortical oW rate includes a uid port substantiallytangentially oriented with respect to said vortex chamber forincrementally influencing the rate of vortex flow in said chamber.

7. The apparatus of claim 6 wherein said means for providing said tirstand second vortical tlow rates further includes a second fluid portsubstantially tangentially oriented with respect to said vortex chamberin a direction for incrementally influencing said vortical ow rate in anopposite rotational direction than said rst fluid port.

8. The apparatus of claim 1 wherein said means for providing said rstand second vortical rates includes means for incrementally varying theow rate of said uid into said chamber.

9. The apparatus of claim 1 wherein said pressure responsive meansincludes a pick olf tube axially lined with and axially spaced from saidexhaust port to receive the flow therefrom thereby providing a pressurein said tube being indicative of said first and second stable pressuredistribution.

10. The apparatus of claim 1 wherein said pressure responsive meansincludes a fluid passage substantially radially communicating with saidexhaust port thereby providing a pressure in said passage beingindicative of said rst and second stable pressure distribution.

References Cited UNITED STATES PATENTS OTHER REFERENCES Mayer, Endre A.et al.,.Control Characteristics of Vortex Valves. In Proceedings of theFluid Amplification Symposium, May 1964, vol. II (pp. 61-76 relied on),Harry Diamond Laboratories, Army Materiel Command,

20 Washington 25, D.C.

M. CARY NELSON, Primary Examiner WILLIAM R, CLINE, Assistant Examiner

